This invention relates to a fuse head, wherein the adherence of the priming explosive to the basic module containing conductive electrodes is enhanced.
Primer caps are generally considered as detonating means that produce a pressure shock which ignites a downstream explosive charge. Ignition caps, the other hand, produce a flame which is then used for ignition of a propellant charge. Since primer caps and ignition caps are substantially identical in construction and differ primarily in the choice of priming explosives, in order to simplify the description of the invention, reference has been made to Fuse Heads.
On pages 28 and 29 of the brochure entitled "Military Initiation Devices", produced in 1988 by Dynamit Nobel AG, Kaiserstr. 1, 5210 Troisdorf, Germany, there is shown a fuse head consisting of a basic module which has electrical connecting wires running through it, and an insulating pole body which is arranged on the basic module. The pole body has a rectangular cross-section, and both its broad faces are covered with copper. An incandescence bridge is applied to the pole body, and each of the ends of said bridge is connected to one of the copper coatings via a soldered joint. At the end of the pole body nearest to the basic module, each of the connecting wires is likewise soldered on both broad faces to the covering of copper. The priming explosive comprises a first and a second priming explosive, which are applied in a bath in a plurality of dipping operations. The first priming explosive is so arranged that it surrounds the incandescence bridge. The second priming explosive forms the outer envelope and is coated with a varnish film for protection.
U.S. Pat. No. 4,152,988 describes a comparable design, though without a pole body. Instead, electrically conductive pole supports run through a basic module, and on the ignition side their ends are connected direct to an incandescence bridge. The incandescence bridge is surrounded by a priming explosive. The priming explosive is again protected externally by a film of varnish.
Both these designs for detonators or fuse heads have the drawback that in hostile ambient conditions as a result of shocks, impacts, vibrations and rotations, the adherence of the priming explosive (or first and second priming explosives) to the basic module is insufficient, and this can cause the detonator to fail.